While the majority of golf balls today are solid, back in the thirties, golf balls were generally only of wound construction. The wound ball was comprised of a center, windings, and a cover. One day, Philip E. Young decided to see if the wound golf ball center he was playing was concentric and asked his golfing partner, a dentist, to x-ray the ball. Sure enough, the x-ray showed that the center of his ball was not concentric. As a result, Mr. Young founded the Acushnet Process Company and began making golf balls that were all x-ray inspected for concentricity.
Heretofore, x-ray inspection of both solid and wound golf balls has been accomplished using two methods. The first method is the golden image process, which consists of taking an image of a “perfect” specimen (a control), placing it into memory, taking subsequent images of samples, and comparing them to the image of the “perfect” specimen. The differences between the “perfect” image and the specimen are used to determine the amount of error in the specimen.
The second method, typically for use on solid balls, includes the steps of x-raying the specimen in such a manner that both the core and the cover are displayed. X-raying the ball in this manner allows direct measurement of the thickness of the cover. This process generally requires the use of lower energy x-rays to so that the cover material can be seen clearly in the resulting image. Many times, the use of lower power causes the edges of the image to become distorted or less clear. The specimen can be doped to assist in cover detection.
Both methods may also include the step of doping the specimen so that the specimen is easier to x-ray. Doping a specimen, however, can have adverse effects on the product. The golden image process is additionally subject to error if the standard is at all less than perfect. Further, the positioning of the golf ball must be perfect. Any wobble in the fixture that holds the ball will affect the golden image test.
There are other limitations inherent in the micro focal x-ray machines that are utilized in industries such as the medical, integrated circuit, and printed circuit board industries. It should also be noted that simply using a micro focal x-ray is not sufficient to produce the sharp images required for many imaging techniques. The device for converting x-rays to visible light, called the image intensifier, must have sufficient resolution to produce a high quality image. Resolution is usually measured in line pairs per millimeter. For example, if an image intensifier has a resolution of 4 line pairs per millimeter and an optical gain of 2 it would be able to resolve an object ⅛ millimeter in size.
Because of these limitations and problems, there is, therefore, a need for more suitable methods of determining the concentricity and dimensions of golf ball components using x-rays. Such a method is presented by the present invention.